package main

// range iterates over elements in a variety of built-in data
// structures.

import "fmt"

func main() {
	// use range to sum the numbers in a slice
	nums := []int{2, 3, 4}
	sum := 0
	for _, num := range nums {
		sum += num
	}
	fmt.Println(sum)

	// range on arrays and slices provides both the index and value
	// for each entry
	for i, num := range nums {
		if num == 3 {
			fmt.Println(i, num)
		}
	}

	// range on map iterates over key/value pairs.
	kvs := map[string]string{
		"a": "apple", "b": "banana",
	}
	for k, v := range kvs {
		fmt.Printf("%s -> %s\n", k, v)
	}

	// range can also iterate over just the keys of a map
	for k := range kvs {
		fmt.Println("key:", k)
	}

	// range on strings iterates over Unicode code points.
	// The first value is the starting byte index of the rune
	// and the second the rune itself.
	for i, c := range "go" {
		fmt.Println(i, c)
	}
}
